According to the involved area and illness course, MND can be divided into several types, but amyotrophic lateral sclerosis ( ALS) and progressive muscular atrophy ( PMA) are the main types. 根据病变累及部位及病程可分为许多类型,其中最主要的有肌萎缩侧索硬化(amyotrophiclateralsclerosis,ALS)和进行性脊肌萎缩症(Progressivemuscularatrophy,PMA)。